Laser marking is commonly used on metal components, and is based on the changes that develop in the material due to localized heating by the laser radiation. Various ways of laser marking may be distinguished. Some are described hereafter. Engraving is the removal of material to a depth of 10 to 50μητι. The laser is used to create a groove in the material and due to melting and evaporation, material is removed to form the groove. Ablation is the evaporation of material by extremely fast laser pulses. The processed material evaporates and fumes are exhausted to prevent re-deposition. Tempering, also called annealing, is the main method for marking steel components. The heat of the laser tempers the steel which changes reflectivity and/or surface structure, leading to a visible mark.
The laser mark on a component surface generally comprises information such as the manufacturer's name and a product type number or serial number etc. This information identifies the product and the maker, but because it is standard information that may be found on any component of a particular type, the information is easy to replicate by counterfeiters. Counterfeiting is detrimental both for the purchaser of a counterfeit article and for the genuine manufacturer.
Consequently, there is a need for a method of providing metal components with an identification mark which is difficult to copy and which makes the component easy to authenticate.